1. Field of the Invention
The present invention relates to a dielectric laminated device to be used for the high frequency wireless apparatuses such as portable telephones, and a manufacturing method thereof.
For example, the dielectric laminated resonator as a dielectric laminated device shown herein may be used solely as a resonator element for a high frequency oscillating circuit, and besides, the plural dielectric laminated resonators are used for combining to constitute a dielectric filter which operates as a band pass filter or a band elimination filter.
2. Description of the Related Art
In recent years, with the development of mobile communication, there have been strong demands for miniature portable telephone apparatuses which are convenient to carry with. Especially, because a dielectric filter using a dielectric laminated resonator is one of the most important parts of the high frequency parts to be used for the wireless circuit of the portable telephones, its formation into miniature size and high performance is strongly demanded.
Hereinafter, referring to the drawings, an example of the conventional dielectric laminated resonator as mentioned above is explained. FIG. 19 shows a disassembled perspective view of a conventional dielectric laminated resonator. FIG. 20 shows a sectional view of a plane including the line 20xe2x80x9420 in FIG. 19. Further, FIG. 21 shows a sectional view of a plane including the line 21xe2x80x9421 in FIG. 19.
In FIGS. 19, 20, and 21, a strip line 202 is formed on the first dielectric sheet 201, and the dielectric sheets 201 and 203 which are laminated on the upper and lower parts of the strip line 202, are put between the shield electrodes 204. By grounding an end of the strip line 202 through the grounding electrode 205, a tip short-circuited strip line resonator is constituted. With the frequency at which the length of the strip line becomes xc2xc wavelength, the impedance at the open end becomes infinitive and parallel resonance occurs. The dielectric laminated resonator of such a structure is disclosed, for example, in Japanese Patent Laid-open No. H2-290303, FIG. 1.
However, according to the constitution as described above, it is possible to make the resonator thin and small size, but due to the formation of the strip line by screen printing, it is difficult to form the line thickness to more than 20 xcexcm, and due to the formation of the convex part by forming a strip line on the dielectric sheet, the edge on the lateral side of the strip line crashes, leading to thinning of the line thickness on the lateral side part of the strip line. Accordingly, the high frequency current concentrates on the lateral side of the strip line, thereby providing the problems such as enlargement of the conduction loss of the strip line and lowering of unloaded Q.
An object of the present invention is to provide a dielectric laminated device which can improve the reliability of mounting of the dielectric laminated device and its manufacturing method. Another object of the present invention is to provide a miniature, low cost dielectric laminated device while maintaining favorably the performance of the dielectric laminated device, and its manufacturing method.
In order to attain the above objects, a dielectric laminated device of the present invention comprises: a dielectric member including a low temperature sintering material; a strip line buried in said dielectric member; and an input and output electrode connected to said strip line and exposed to a surface along a line direction of said strip line out of outer surfaces of said dielectric member.
A dielectric laminated device of the present invention comprises: a dielectric member containing a low temperature sintering material; and a strip line buried in said dielectric member;
wherein the thickness or the width of said strip line being varied on the basis of a line direction of said strip line.
A dielectric laminated device of the present invention comprises: a dielectric member containing a low temperature sintering material; a plurality of strip lines buried in said dielectric member; a coupling electrode buried in said dielectric member on one or other side of said plurality of strip lines; and an input and output coupling electrode buried in said dielectric member on one or the other side of said plurality of strip lines,
wherein a thickness of said strip line being larger than each thickness of said coupling electrode and said input and output coupling electrode.
A dielectric laminated device of the present invention comprises: a dielectric member formed by laminating a plurality of dielectric sheets, a shield electrode disposed on an outer surface of said dielectric member, a strip line formed by an electrode material buried in an inside of a part of said plural dielectric sheets, and an input and output electrode connected to said strip line, and exposed to a surface along a line direction of the strip line out of an outer surfaces of said dielectric member.
A dielectric laminated device of the present invention comprises: a dielectric member formed by laminating a plurality of dielectric sheets including a first, second and third dielectric sheets, a shield electrode disposed on an outer surface of said dielectric member, a first strip line formed by an electrode material buried in an inside of said first dielectric sheet, a second strip line formed by said. electrode material buried in an inside of said second dielectric sheet which is laminated on one of faces of said first dielectric sheet, and a third strip line formed by said electrode material buried in an inside of said third dielectric sheet which is laminated on the other face of said first dielectric sheet,
wherein surfaces of said second and third strip lines are respectively in contact with a surface of said first strip line along a line direction of said first strip line, a length of said second and third strip lines is shorter than a length of said first strip line, an end of said first strip line is electrically opened along with an end of said second and third strip lines, and the other end of said first strip line is electrically connected to a ground electrode disposed outside said dielectric member.
A dielectric laminated filter of the present invention comprises: a first dielectric sheet having a plurality of openings, a plurality of strip lines formed by burying electrodes in said plural openings, a second dielectric sheet laminated on one surface of said first dielectric sheet, a third dielectric sheet laminated on the other surface of said first dielectric sheet, a coupling electrode internally laminated in said second dielectric sheet, for forming a coupling capacity with said plural strip lines, an input and output coupling electrode internally laminated in said third dielectric sheet, for forming an input and output capacity with said plural strip line, a first shield electrode provided on an upper surface of said second dielectric sheet, and a second shield electrode provided on a lower surface of said dielectric sheet,
wherein an end of said plural strip lines is connected to a ground electrode, the other end of said plural strip lines is opened, and said first to third dielectric sheets are calcined in one piece by the use of the same ceramic material.
A method for manufacturing a dielectric laminated device of the present invention comprises: a step for forming an burying space for burying an electric conductive member in a dielectric sheet, an burying step for burying an electric conductive member in said burying space so as to form a strip line and an input and output electrode for connecting said strip line, and a lamination step for forming a laminate by laminating a single or plural other dielectric sheets on a dielectric sheet on which said strip line and said input and output electrode are formed,
wherein said input and output electrode is produced in a manner to expose on a surface along a line direction of said strip line out of outer surfaces of the dielectric laminated device to be manufactured on the basis of said three steps.
A method for manufacturing a dielectric laminated device of the present invention comprises: a step for forming an burying space for burying electric conductive members in a plurality of dielectric sheets, a strip line forming step for forming a strip line by burying an electric conductive member in said burying space in one dielectric sheet out of said plural dielectric sheets, an input and output electrode forming step for forming an input and output electrode by burying a conductive member in said burying space of another dielectric sheet out of said plural dielectric sheets, and a laminating step for laminating dielectric sheets burying with said conductive members so as to connect said input and output electrode with said strip line, and forming a laminate by laminating a single or plurality of other dielectric sheets on said laminated dielectric sheets,
wherein said input and output electrode is manufactured in a manner to be exposed to a surface lying along a line direction of said strip line out of outer surfaces of said laminate.
A method for manufacturing a dielectric laminated device of the present invention comprises: a step for forming an burying space for burying electric conductive members in a dielectric sheet, an burying step for burying an electric conductive member in said burying space to form a strip line, and a laminating step for forming a laminate by laminating a plurality of dielectric sheets on which said strip line is formed and other dielectric sheet,
wherein, of the strip lines burying in each layer of said plural dielectric sheets, a line length of one strip line is longer than the line length of other strip lines.
As described above, according to the present invention, by burying an electrode in the opening of the dielectric sheet and forming a strip line and an input and output electrode, small sized, highly reliable dielectric laminated device and its manufacturing method can be realized while favorably maintaining the performance of the resonator.